A month passed. Two months passed. Then three and now almost four.

‘I test negative now,” she said. “I’m definitely better than I was. But I can’t go out without a tank of oxygen. I can’t act. When I speak, it feels like I’m rushing too much. I still get fevers. I still can’t do much of what I used to do. I’m not getting fully better, even after four months.”

People kept saying: “Be patient,” and she tried to be. “But there is only so much one can take. I just wish I knew what was going on.”

So do a lot of researchers, physicians and other medical professionals.

As they try to unwind this brand-new virus, many mysteries remain. Why are certain people asymptomatic? Do they have fiercer immune systems or are they lucky in some other way? Why is the virus fatal to some otherwise healthy people? While many COVID-19 deaths are predictable —the old, the obese, the severely preconditioned — quite a few aren’t. What explains those viral lightning strikes? And what about children? How differently does the virus mess with them?

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Then you get around to the myriad ways the coronavirus undermines the human body: the organs it attacks, the strength of its grip, the dramatically differing slopes of recovery, the preconditions it shrugs at and the ones it cruelly exploits.

Can you get it twice or three times? No one knows. How long do the antibodies last? No one knows. How much protection do they provide? No one knows. How much help will a vaccine really be? Again, no one knows.

Truly, the questions do not end, and now we have another one: Why are some people who seem to have beaten the infection still not getting well? What explains the long-haulers?

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“A whole host of people do not get better after two weeks,” said Noah Greenspan, a cardiopulmonary rehabilitation specialist in Manhattan and founder of the Pulmonary Wellness Foundation. “Many of them are young, healthy people like Gaby, the last people you would expect.” They’ve packed his practice, he said, arriving with a wide range of lingering symptoms.

Greenspan recently launched what he calls the COVID Rehabilitation & Recovery Bootcamp, an online resource for patients whose symptoms just won’t go away. The no-cost program (pulmonarywellness.org) suggests exercises, breathing techniques and other wellness therapies and also provides patient education and support. There also is guidance from other medical specialists.

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“This coronavirus is extremely opportunistic,” Greenspan said. “Not only does it affect the respiratory system, but it also affects the cardiovascular system, the gastrointestinal system and any other system that is your potential weakness. The virus will find that weakness and exploit it.” Which is why the nagging cases require a broad, interdisciplinary approach.

If COVID hadn’t been such a crisis, he said, far more of these patients would have been treated in emergency rooms and intensive care units. “But those facilities were overloaded, and too many of these patients were essentially sent home and told to fend for themselves,” Greenspan said.

In many cases, they are still fending.

As for Gabriela Ochoa Perez, she said she’s taking the virus far more seriously than many of her young friends are. She said she’s open to almost anything that might help return her fully to health.